kokoko3k, thanks. I'm not using mplayer, but rather our own code. I just mentioned mplayer as an example of a similar program that might be affected in the same ways (if multiple instances at once are run across multiple screens).

I am using YUV overlays, however we have multiple displays. My understanding is that in the second display driven off of the nvidia card, you fake YUV overlays with blits. The rendering is definitely sync'd when XVideoTextureSyncToVBlank is set to 1, and is not when it is set to 0, and the performance with multiple windows being rendered is most definitely as I described. I'm not positive that SDL is actually using hardware surfaces in all cases (I just need to add some code to check), and like I mentioned we are using multiple displays, so some of this could be related to the way display 2 is handled by the driver (not sure if it happens in 2 X screen configs, but it is definitely happening in twinview configs). However, performance is great with the XVideoTextureSyncToVBlank turned off, so thought I'd bring it up here.

Thanks for the tip Phalin, will look into it.

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r.c. mentions that he is using YUV overlays in SDL whith multiple displays, just using multiple instances at once running across multiple screens. I need to do this myself (I have a nvidia quadro), but i cuoldn't find a way to tell SDL in which display it must draw. Is there any SDL function that solves this? Any other approach I can use?